WinUI 3 Preview 4: The target process exited without raising a CoreCLR started event

Describe the bug

The blank WinUI 3 Preview 4 desktop application does not start. The output window shows this error:

The target process exited without raising a CoreCLR started event. Ensure that the target process is configured to use .NET Core. This may be expected if the target process did not run on .NET Core. The program ‘[6384] App15.exe’ has exited with code -2147450740 (0x8000808c).

Steps to reproduce the bug Steps to reproduce the behavior:

1. Create a new “Blank App (WinUI in Desktop)”
2. Add a reference to the NuGet Package Entity

    <PackageReference Include="Microsoft.EntityFrameworkCore.SqlServer" Version="5.0.3" />

1. Try to debug the app. It builds, gets deployed, but gets not started
2. The output window shows the mentioned error

Expected behavior The application should start after adding a reference to the NuGet package Microsoft.EntityFrameworkCore.SqlServer

Version Info WinUI 3 Preview 4 (but also happens on Preview 3). I include here my .csproj for details

<Project Sdk="Microsoft.NET.Sdk">
  <PropertyGroup>
    <OutputType>WinExe</OutputType>
    <TargetFramework>net5.0-windows10.0.18362.0</TargetFramework>
    <TargetPlatformMinVersion>10.0.17134.0</TargetPlatformMinVersion>
    <RootNamespace>App15</RootNamespace>
    <ApplicationManifest>app.manifest</ApplicationManifest>
    <Platforms>x86;x64;arm64</Platforms>
    <RuntimeIdentifiers>win10-x86;win10-x64;win10-arm64</RuntimeIdentifiers>
  </PropertyGroup>

  <ItemGroup>
    <PackageReference Include="Microsoft.EntityFrameworkCore.SqlServer" Version="5.0.3" />
    <PackageReference Include="Microsoft.WinUI" Version="3.0.0-preview4.210210.4" />
    <Manifest Include="$(ApplicationManifest)" />
  </ItemGroup>
</Project>

Windows app type:

UWP	Win32
	Yes

Windows 10 version	Saw the problem?
Insider Build (xxxxx)
October 2020 Update (19042)
May 2020 Update (19041)	Yes
November 2019 Update (18363)
May 2019 Update (18362)
October 2018 Update (17763)
April 2018 Update (17134)
Fall Creators Update (16299)
Creators Update (15063)

Device form factor	Saw the problem?
Desktop	Yes
Xbox
Surface Hub
IoT

[evelynwu-msft]

Yep, WinDBG; VS is frustratingly terse when it comes to issues that occur early during app startup.

Closing this issue since it’s been reported to VS.

[thomasclaudiushuber]

Thank you @alwu-msft. Omg, you’re right, why the heck didn’t I try the WAP project with a .NET 5 WPF project?! 😃

Yes, I can confirm, it’s an issue that is related to the WAP project and the NuGet package. I was able to reproduce it in a .NET 5 WPF app when packaging it as MSIX via WAP project.

I reported the error via Visual Studio Send Feedback as you suggested: https://developercommunity2.visualstudio.com/t/windows-application-packaging-project-wap-causes-e/1347957

Please upvote, my friends 🙂

I keep this issue open and will update/close it, as soon as I get feedback from the other channel. But if you, @alwu-msft, think closing this issue now is a better idea, feel free to close it.

PS: How did you get the detailed debug output? Via WinDbg?